Question regarding transcoding threads and priority

[Wallboy]

I was just looking through the command line help and noticed 2 options to use in the transcode module, threads & high-priority. I've never used these options in the past for my streams, but I've noticed that it seems all my cores are in use when transcoding without specifying how many threads to use. I'm on a Q6600 quad core, so i'm assuming VLC automatically uses all available threads without the need to specify how many to use and the option is only for using less threads for whatever reason? Also what does high-priority option do if enabled? When should one use this or not use this? Is it the same as just turning up the priority in task manager for vlc.exe? Thanks.